docs: def Throughput(self):
          """Combined throughput from multiplying all the components together.
  
          Returns
          -------
          throughput : `~pysynphot.spectrum.TabularSpectralElement` or `None`
              Combined throughput.
  
          """
          try:
              throughput = spectrum.TabularSpectralElement()
  
              product = self._multiplyThroughputs(0)
  
              throughput._wavetable = product.GetWaveSet()
              throughput._throughputtable = product(throughput._wavetable)
              throughput.waveunits = product.waveunits
              throughput.name='*'.join([str(x) for x in self.components])
  
  ##            throughput = throughput.resample(spectrum._default_waveset)
  
              return throughput
  
          except IndexError:   # graph table is broken.
              return None